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The first of these was, incidentally, also the basis for the colloquium talk preceeding the one on 2-vector bundles and elliptic cohomology which I mentioned recently. I conjecture that there is more to this conjunction of talks than meets the eye.

As introductions to the motivation and logic of FRS, I can stronly recommend the following texts

Posted by Urs Schreiber

February 7, 2006

Philosophy of Real Mathematics

Posted by Urs Schreiber

While I am struggling to understand elliptic cohomolohy, David Corfield, over on his weblog, has taken a look at the literature from the perspective of a philosopher of real mathematics.

“Real” here is meant in the sense of “what active mathematicians are really concerned with”, as opposed to an eternal occupation with Russel’s paradox and Gödel’s incompleteness. Have a look at his book for more.

To me, the interesting point to be addressed here is how we actually go about identifying the structures that we feel should be out there. As in: “How should we really think about elliptic cohomology?”, or the outworn but still curiously elusive “What is string theory?”. And maybe this one: “Is there a relation between these two questions?”

Posted by Urs Schreiber

February 2, 2006

Seminar on 2-Vector Bundles and Elliptic Cohomology, I

Posted by Urs Schreiber

We currently have a series of seminars here on tensor categories and their application in CFT. After having heard talks about the basics of tensor categories and the way they appear in the FRS formalism of CFT, today Birgit Richter gave an introductory review of the work

I use this opportunity to remind the (potential) readers of any of these blogs once again that the way to read blogs without becoming insane is to use an RSS reader software. The latest Mozialla Thunderbird has one built in.

Orbifold String Topology: Paths in Smooth Categories

Posted by Urs Schreiber

with the honest intent to write something about this. But one main concept used in this work is a notion of loop space of an orbifold, expressed in groupoid language as the loop groupoid, and it turned out that I had my own ideas on this object. Thinking about this interfered with my intent to read the rest of the paper. So in order to get this out of the way first I here present instead some observations on an alternative perspective on the loop groupoid.